LAUSR

Transanal endoscopic microsurgery (TEM) is a minimally invasive technique that can be considered for removal of retrorectal dermoid cysts because of its clear advantages over major surgery (less pain, faster recovery, no perineal wounds and avoidance of possible removal of the coccyx). We report a series of three cases of TEM for dermoid cysts. Diagnosis was made in all cases by magnetic resonance imaging (MRI) previously carried out on request of the general practitioner when patients complained of rectal pain, difficult defecation and sense of perineal mass. Rectal examination revealed in all cases an elastic, almost spherical, partially fixed, painless mass above the sphincter ring, covered by normal rectal mucosa. Two lesions were located posteriorly and one anteriorly. All patients underwent preoperative pancolonoscopy, endorectal ultrasound and further MRI to determine size, location and any possible local invasion of the mass. The mean distance of the distal margin of the lesion from the anal verge was 5 cm. Patient characteristics are shown in Table 1. All patients underwent full bowel preparation and had antibiotic and antithrombotic prophylaxis. Preoperative biopsies of the lesions were not performed because both ultrasound and MRI demonstrated clear signs that they were benign and to avoid a possible introduction of infection. All procedures were performed under general anesthesia. Two patients were operated on in the lithotomy position and one patient in the prone position depending on the location of the cyst. We used the original TEM equipment (Richard WolfKnittlingen, Germany). Pneumorectumwas establishedwith continuous rectal insufflation of carbon dioxide. After the introduction of a rigid rectoscope 14 cm in length and 40 mm in diameter, a transversal full-thickness incision at the level of the protruding mass was performed using an electrosurgical monopolar device. No rupture occurred but the intraoperative needle aspiration of the two larger cysts was required to facilitate both dissection and removal. In the case of the anterior cyst gentle introduction of a finger into the vagina helped to make the procedure safer. The rectal wall defect was transversally closed using a 3/0 monofilament running suture secured with dedicated silver clips after a careful lavage of the cavity with saline and betadine. Mean specimen size was 6 cm (range 4–8 cm). The mean operation time was 65 min (range 35–90 min). No intraoperative complications occurred. The patients’ postoperative course was uneventful, and the mean hospital stay was 2 days (range 1–4 days). Patients were started on a regular diet the day after surgery and were recommended to take oral antibiotics for 7 days after discharge. Among the different developmental cysts, dermoid cysts are those most commonly found in the perirectal space [1] and occur most often in young women [2]. They always have chronic inflammatory adhesions to the muscular fibers of the rectum and the perirectal tissues. The diagnosis is often incidental, although half of the patients complain of chronic perineal pain or other symptoms related to mass Electronic supplementary material The online version of this article (doi:10.1007/s10151-017-1618-8) contains supplementary material, which is available to authorized users.